Is time travel is possible or not

Time travel

time travel

The BBC’s long-running science-fiction series Doctor Who, celebrating its 50th anniversary on 23 November, time travel centres on its eponymous character’s adventures through time and space. But could he really skip between different periods of history at will?

time Travel forwards in time is surprisingly easy. Einstein’s special theory of relativity, developed in 1905, shows that time passes at different rates for people who are moving relative to one another – although the effect only becomes large when you get close to the speed of light.

If one were to leave Earth in a spacecraft travelling at an appreciable fraction of lightspeed, turn around and come back, only a few years might have passed on board but many years could have gone by on Earth. This is known as the “twins paradox”, since a traveller undertaking such a journey would return to find herself much younger than her twin.

There’s only one problem from anyone wishing to get a glimpse of the future – getting back. It would mean travelling faster than light – and that’s not possible.

But there may be an out to be found in general relativity, Einstein’s theory of gravity that unites space and time as “spacetime”, which curves in the presence of mass. It allows for the possibility of wormholes – a kind of tunnel through spacetime connecting otherwise very distant parts of the universe.

If the “mouths” of the wormhole are moving relative to one another, then traversing the bridge between different points in space would also take a traveller to a different point in time to that in which she started.

However it would still be impossible to go back further in time than the point at which the wormhole was created, limiting the options for travel somewhat – and possibly explaining why we haven’t encountered any visitors from the future. If any natural wormholes were formed in the Big Bang, it might be possible to travel to a limited number of points in the past and in the distant universe, but wouldn’t enable one to flit around the cosmos at will as the Doctor seems to do.

More restrictively still, theoretical work by Kip Thorne of Caltech using a partial unification of general relativity with quantum physics suggested that any wormhole that allows time travel would collapse as soon as it formed.

Thorne did, however, resolve an apparent issue that could arise due to by time travel (within the confines of general relativity). The “grandfather paradox” involves going back in time and accidentally killing one’s grandfather before one’s father is conceived – preventing one’s own birth, making it impossible to go back in time and kill one’s grandfather. Thorne found that for point masses traversing a wormhole, no initial conditions create this type of paradox.

That’s good news for anyone worried about people going back and changing the past willy-nilly, but bad news for any Whovians hoping to reverse the decision to cancel the show in 1989 and prevent a 16-year hiatus. That would probably be beyond even the Doctor himself.

In Stephen Hawking’s universe there was no room for God, because the famous cosmologist came to believe that the entirety of existence was created out of, well… nothing.

As he explains in his final book, “Brief Answers to the Big Questions,” before the Big Bang there was nothing, not even a God to create the universe.

“I think the universe was spontaneously created out of nothing according to the laws of science,” Hawking writes. “There is no time for a creator to have existed in.”

He goes on to explain that the only God who could be consistent with the laws of physics would be a deity who never directly influences the workings of the universe.

“These laws may or may not have been decreed by God, but he cannot intervene to break the laws or they would not be laws.”

While the existence of God makes little sense to Hawking, he’s more open to the possibility of something that most people might consider much more far-fetched: time travel.

time travel

Hawking famously held a party for time travelers but did not send out the invitations until after the party. No one showed up for the festivities. But the scientist writes that there is still some hope that traveling back in time could be possible according to the laws of the universe. He pegs this notion on the promise of something called “M theory” that suggests the universe may contain seven hidden dimensions in addition to the familiar four dimensions of space-time travel.

First planted in 1828 by missionary Samuel Ruggles, Kona coffee has achieved international renown. Known for its smooth, rich flavor, it’s now grown on about 600 farms, ranging from less than an acre to 40 acres in size. Most of the farms lie between the cool 800- and 2,500-foot elevations of Mauna Loa volcano, and are family owned and operated time travel.

The Kona Coffee Living History Farm is on land first homesteaded in 1900. It provides a glimpse of what daily life was like for its original owner, Japanese immigrant Daisaku Uchida, and his family, circa 1925 to 1945. The Kona Historical Society now owns and oversees the 5½-acre farm, which welcomes visitors for self-guided tours four days a week.

As part of the farm’s “living history” program, docents dressed in period attire talk about the buildings and demonstrate traditional crafts, agricultural activities and everyday chores. All of them grew up in Kona as members of coffee-growing families, and they pepper their narrations with personal stories.

Displayed in the farmhouse and on the grounds are numerous artifacts donated by the Uchidas and other local families, including a kudo (wood-burning stove), a hagama (rice cooker), a tansu (dresser), a yanagi kori (wicker suitcase), a charcoal- heated iron, a vintage treadle sewing machine and ceilings made of rice bags. Take a close look at the hoshidana (drying platform), which has a rolling roof. When the sun was shining, workers would pull back the roof so the coffee beans spread on the platform beneath it would dry. This took three days to two weeks, depending on weather conditions. On rainy days, they closed the roof to prevent the beans from getting wet and spoiling.

During your visit, you can also try your hand at making musubi (rice balls); stroll through the coffee and macadamia nut orchards; pick ripe coffee cherries during the harvest season (which usually runs from September through December); say hello to Charlie, the resident donkey; and buy bags of freshly roasted coffee to take home (this is still a working farm).

Kona Coffee Living History Farm

The Kona Coffee Living History Farm is at 82-6199 Mamalahoa Highway, Kealakekua, Big Island. Hours are 10 a.m. to 2 p.m. Monday through Friday (please arrive by 1 p.m. to allow enough time for a full tour). Admission is $15 for adults, $9 for college students with ID and $5 for youth ages 7-17. KHS members and children age 7 and younger are admitted free. (808) 323-2006; www.konahistorical.org.

A version of this story appeared in the Spring/Summer 2012 print issue of Huakai, a bi-annual publication published by aio Media in partnership with Starwood Properties.